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https://issues.apache.org/jira/browse/HBASE-14404?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14791536#comment-14791536
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Lars Hofhansl commented on HBASE-14404:
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Looking at the patch detail now. It does not allow for sticking with the
default setup for HDFS. Whatever the HBase setting is will override whatever
was set globally for HDFS, that might be surprising.
> Backport HBASE-14098 (Allow dropping caches behind compactions) to 0.98
> -----------------------------------------------------------------------
>
> Key: HBASE-14404
> URL: https://issues.apache.org/jira/browse/HBASE-14404
> Project: HBase
> Issue Type: Task
> Reporter: Andrew Purtell
> Assignee: Andrew Purtell
> Fix For: 0.98.15
>
> Attachments: HBASE-14404-0.98.patch
>
>
> HBASE-14098 adds a new configuration toggle -
> "hbase.hfile.drop.behind.compaction" - which if set to "true" tells
> compactions to drop pages from the OS blockcache after write. It's on by
> default where committed so far but a backport to 0.98 would default it to
> off. (The backport would also retain compat methods to LimitedPrivate
> interface StoreFileScanner.) What could make it a controversial change in
> 0.98 is it changes the default setting of
> 'hbase.regionserver.compaction.private.readers' from "false" to "true". I
> think it's fine, we use private readers in production. They're stable and do
> not present perf issues.
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